320
12. Comparing months when the value of an element is very much above the average with those where it is much below it, we obtain certain information which is exhibited in the following table :--
Table III.
Results of Comparison of Mean Monthly Meteorological Elements with 5-yearly Means.
Extremes only, (1884-1889) 6 Years,
Element.
Extreme.
No. of Months used in the
Temper-
Barometer.
ature.
Vapor Rainfall Tension. (actual).
Rainfall Velocity Direction Amount
of (propor- tional). Wind. Wind. Cloud.
of
of
Mean.
High,
18
Barometer,
Low,
21
ill. +0.039 -0.7 -0.043 +0.8
о
in.
in.
in. -0.013 -0.01 -0.16 -0.1 +0.036 +2.11 +0.45 +0.4
}}1.
• 17
+3
Temperature,
High,
+
Low,
2*
20
18
-0.014 +0.013
+2.0 -1.5
+0,046 -0.024
+1.19 +0.31 +0.63 +0.03 +0.1
-0.4
+8
-7
77
+4
Vapor Tension,...
High,.... 23 Low,
15
-0.014 +0.015
+1.4 -1.1
+0.052 -0.053
+2.87 - 1.67
+0.55 +0.3 -0.37
+5
+3
-0.3
Rainfall,
Excess,
(proportional,
18 Defect,... 18
-0.023 +0.5 +0.018 +0.3
+0.032 +8.12 -0.006 -3.45
+1.28 +0.2 -0.70 -0.2
-3
+7
+3
-3
Velocity of Wind,{
High,
12
Low,
16
-0.011 -0.004
+0.3 +0.8
+0.022 +2.89 +0.24 +0.008 -1.25 -0.16
+2.5
-2.2
T. +
Direction of Wind,
Positive, 13 Negative, 18
-0.002 -0.006
+1.3 -0.4
+0.031 -2.24 -0.13 -0.1 -0.010 +0.31 +0.07 +0.3
+26
-19
+1
-2.
Amount Clond,... {
17
Excess, Defect,... 14
74
-0.025
+2.12 +0.49 +0.3
-0.020
- 1.75
-0.38
-0.3
+0.2 +0.027 +0.008 +0.1
77
4
+13 - 13
13. Months with pressure exceeding the mean are on the whole colder, drier and clearer than other months in which pressure is deficient. If the temperature exceeds the mean, the vapour tension as a rule does so also, but not the cloudiness. Excess of rainfall causes excess of vapour tension, which occurs together with increased cloudiness. When the velocity of the wind exceeds the average, the rainfall is usually also above the average. The temperature does not seem to be affected by the amount of rain. The hot weather preceding rain-storms is balanced by the cold during the rainfall. There is not much to be learned from the direction of the wind in this connection as the results during the N.E. and S.W. monsoon are treated together. They must be treated separately, but that is better done by investigating wind-roses. On the whole a hot summer follows a warm winter, and a cold winter is followed by a cool summer.
14. The following tables exhibit wind-roses for Hongkong computed from the three years 1889- 1891 inclusive. When the result depends on less than 4 days observations an asterisk is prefixed. At all seasons of the year East winds are most common-the Colony being situated within the region of the trade-wind; but from June till September, there is another southerly maximum caused by the monsoon. During the winter the barometer is high during N and low during S winds, but in the summer it is high with E winds and low with NE winds, which latter blow during typhoons, but it is also low when the SW monsoon blows. In winter, the temperature is highest with S and lowest with N wind, and in suminer, it is highest with SW and lowest with E winds, but in summer, the direction of the wind does not affect the temperature so much as in winter. In winter, the dampness is greatest with S and lowest with N winds, but in summer, it is greatest with E winds. The air is
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